title: Mutations affecting G-protein subunit α11 in hypercalcemia and hypocalcemia.
abstract: BACKGROUND
  Familial hypocalciuric hypercalcemia is a genetically heterogeneous disorder with three variants: types 1, 2, and 3. Type 1 is due to loss-of-function mutations of the calcium-sensing receptor, a guanine nucleotide-binding protein (G-protein)-coupled receptor that signals through the G-protein subunit α11 (Gα11). Type 3 is associated with adaptor-related protein complex 2, sigma 1 subunit (AP2S1) mutations, which result in altered calcium-sensing receptor endocytosis. We hypothesized that type 2 is due to mutations effecting Gα11 loss of function, since Gα11 is involved in calcium-sensing receptor signaling, and its gene (GNA11) and the type 2 locus are colocalized on chromosome 19p13.3. We also postulated that mutations effecting Gα11 gain of function, like the mutations effecting calcium-sensing receptor gain of function that cause autosomal dominant hypocalcemia type 1, may lead to hypocalcemia.
  
  
  METHODS
  We performed GNA11 mutational analysis in a kindred with familial hypocalciuric hypercalcemia type 2 and in nine unrelated patients with familial hypocalciuric hypercalcemia who did not have mutations in the gene encoding the calcium-sensing receptor (CASR) or AP2S1. We also performed this analysis in eight unrelated patients with hypocalcemia who did not have CASR mutations. In addition, we studied the effects of GNA11 mutations on Gα11 protein structure and calcium-sensing receptor signaling in human embryonic kidney 293 (HEK293) cells.
  
  
  RESULTS
  The kindred with familial hypocalciuric hypercalcemia type 2 had an in-frame deletion of a conserved Gα11 isoleucine (Ile200del), and one of the nine unrelated patients with familial hypocalciuric hypercalcemia had a missense GNA11 mutation (Leu135Gln). Missense GNA11 mutations (Arg181Gln and Phe341Leu) were detected in two unrelated patients with hypocalcemia; they were therefore identified as having autosomal dominant hypocalcemia type 2. All four GNA11 mutations predicted disrupted protein structures, and assessment on the basis of in vitro expression showed that familial hypocalciuric hypercalcemia type 2-associated mutations decreased the sensitivity of cells expressing calcium-sensing receptors to changes in extracellular calcium concentrations, whereas autosomal dominant hypocalcemia type 2-associated mutations increased cell sensitivity.
  
  
  CONCLUSIONS
  Gα11 mutants with loss of function cause familial hypocalciuric hypercalcemia type 2, and Gα11 mutants with gain of function cause a clinical disorder designated as autosomal dominant hypocalcemia type 2. (Funded by the United Kingdom Medical Research Council and others.).
authors.affiliation: Academic Endocrine Unit, Nuffield Department of Clinical Medicine (M.A.N., F.M.H., S.A.H., V.N.B., R.A.H., R.V.T.), and Sir William Dunn School of Pathology (N.R.), University of Oxford, and the Oxford Molecular Genetics Laboratory, Churchill Hospital (T.C.) - all in Oxford, United Kingdom; Core Research Facilities, University of Utah, Salt Lake City (M.R.H.); and Indiana University School of Medicine, Indianapolis (H.H.).
authors.forename: M Andrew
authors.initials: MA
authors.lastname: Nesbit
authors.affiliation: Academic Endocrine Unit, Nuffield Department of Clinical Medicine (M.A.N., F.M.H., S.A.H., V.N.B., R.A.H., R.V.T.), and Sir William Dunn School of Pathology (N.R.), University of Oxford, and the Oxford Molecular Genetics Laboratory, Churchill Hospital (T.C.) - all in Oxford, United Kingdom; Core Research Facilities, University of Utah, Salt Lake City (M.R.H.); and Indiana University School of Medicine, Indianapolis (H.H.).
authors.forename: Fadil M
authors.initials: FM
authors.lastname: Hannan
authors.affiliation: Academic Endocrine Unit, Nuffield Department of Clinical Medicine (M.A.N., F.M.H., S.A.H., V.N.B., R.A.H., R.V.T.), and Sir William Dunn School of Pathology (N.R.), University of Oxford, and the Oxford Molecular Genetics Laboratory, Churchill Hospital (T.C.) - all in Oxford, United Kingdom; Core Research Facilities, University of Utah, Salt Lake City (M.R.H.); and Indiana University School of Medicine, Indianapolis (H.H.).
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Howles
authors.affiliation: Academic Endocrine Unit, Nuffield Department of Clinical Medicine (M.A.N., F.M.H., S.A.H., V.N.B., R.A.H., R.V.T.), and Sir William Dunn School of Pathology (N.R.), University of Oxford, and the Oxford Molecular Genetics Laboratory, Churchill Hospital (T.C.) - all in Oxford, United Kingdom; Core Research Facilities, University of Utah, Salt Lake City (M.R.H.); and Indiana University School of Medicine, Indianapolis (H.H.).
authors.forename: Valerie N
authors.initials: VN
authors.lastname: Babinsky
authors.affiliation: Academic Endocrine Unit, Nuffield Department of Clinical Medicine (M.A.N., F.M.H., S.A.H., V.N.B., R.A.H., R.V.T.), and Sir William Dunn School of Pathology (N.R.), University of Oxford, and the Oxford Molecular Genetics Laboratory, Churchill Hospital (T.C.) - all in Oxford, United Kingdom; Core Research Facilities, University of Utah, Salt Lake City (M.R.H.); and Indiana University School of Medicine, Indianapolis (H.H.).
authors.forename: Rosie A
authors.initials: RA
authors.lastname: Head
authors.affiliation: Academic Endocrine Unit, Nuffield Department of Clinical Medicine (M.A.N., F.M.H., S.A.H., V.N.B., R.A.H., R.V.T.), and Sir William Dunn School of Pathology (N.R.), University of Oxford, and the Oxford Molecular Genetics Laboratory, Churchill Hospital (T.C.) - all in Oxford, United Kingdom; Core Research Facilities, University of Utah, Salt Lake City (M.R.H.); and Indiana University School of Medicine, Indianapolis (H.H.).
authors.forename: Treena
authors.initials: T
authors.lastname: Cranston
authors.affiliation: Academic Endocrine Unit, Nuffield Department of Clinical Medicine (M.A.N., F.M.H., S.A.H., V.N.B., R.A.H., R.V.T.), and Sir William Dunn School of Pathology (N.R.), University of Oxford, and the Oxford Molecular Genetics Laboratory, Churchill Hospital (T.C.) - all in Oxford, United Kingdom; Core Research Facilities, University of Utah, Salt Lake City (M.R.H.); and Indiana University School of Medicine, Indianapolis (H.H.).
authors.forename: Nigel
authors.initials: N
authors.lastname: Rust
authors.affiliation: Academic Endocrine Unit, Nuffield Department of Clinical Medicine (M.A.N., F.M.H., S.A.H., V.N.B., R.A.H., R.V.T.), and Sir William Dunn School of Pathology (N.R.), University of Oxford, and the Oxford Molecular Genetics Laboratory, Churchill Hospital (T.C.) - all in Oxford, United Kingdom; Core Research Facilities, University of Utah, Salt Lake City (M.R.H.); and Indiana University School of Medicine, Indianapolis (H.H.).
authors.forename: Maurine R
authors.initials: MR
authors.lastname: Hobbs
authors.affiliation: Academic Endocrine Unit, Nuffield Department of Clinical Medicine (M.A.N., F.M.H., S.A.H., V.N.B., R.A.H., R.V.T.), and Sir William Dunn School of Pathology (N.R.), University of Oxford, and the Oxford Molecular Genetics Laboratory, Churchill Hospital (T.C.) - all in Oxford, United Kingdom; Core Research Facilities, University of Utah, Salt Lake City (M.R.H.); and Indiana University School of Medicine, Indianapolis (H.H.).
authors.forename: Hunter
authors.initials: H
authors.lastname: Heath
authors.affiliation: Academic Endocrine Unit, Nuffield Department of Clinical Medicine (M.A.N., F.M.H., S.A.H., V.N.B., R.A.H., R.V.T.), and Sir William Dunn School of Pathology (N.R.), University of Oxford, and the Oxford Molecular Genetics Laboratory, Churchill Hospital (T.C.) - all in Oxford, United Kingdom; Core Research Facilities, University of Utah, Salt Lake City (M.R.H.); and Indiana University School of Medicine, Indianapolis (H.H.).
authors.forename: Rajesh V
authors.initials: RV
authors.lastname: Thakker
mesh_terms: D002118:Calcium / Q000032:analysis; D004252:DNA Mutational Analysis; D045604:Extracellular Fluid / Q000737:chemistry; D005260:Female; D044385:GTP-Binding Protein alpha Subunits / Q000737:chemistry / Q000235:genetics*; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000235:genetics*; D005799:Genes, Dominant; D018095:Germ-Line Mutation; D006579:Heterozygote; D006801:Humans; D006934:Hypercalcemia / Q000235:genetics*; D006996:Hypocalcemia / Q000235:genetics*; D008297:Male; D008958:Models, Molecular; D009154:Mutation; D010375:Pedigree; D011487:Protein Conformation; D015398:Signal Transduction
chemical_list: C554062:GNA11 protein, human; D044385:GTP-Binding Protein alpha Subunits; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D002118:Calcium